Without a router or Layer 3 device capable of sending IGMP queries, the 3300 series switches cannot provide dynamic multicast support. They are only capable of IGMP Snooping, which requires a device that sends the queries.

To support multicasting without a querier, you would have to use static multicast groups and assign the ports that will participate in the group. See the following link to the online CLI Guide for the "bridge multicast" commands:

http://support.dell.com/support/edocs/network/pc33xx/en/CLI/J0926a00/addresst.htm#1006719